Whiter white in cycles
More light is what you need. Try to ensure that your lamps are not all placed near the stones, so as to give a more even illumination.



Keep in mind that the environment is directly affecting the brightness/color of reflective objects, so set the world color to at least a brighter gray, though white is probably to much. 

Imagine (or look at reference images) the kind of ambient light there is reflected from the roof/walls and floor of a large, brightly lit ice rink/arena. Sort of a soft grayish white. Here's what I used for the image above (I didn't use any method to come up with this value, I just eyeballed it):



Note that enabling AO will really brighten things up, but I'm not sure that's what you want. (you can also use the AO pass to get finer control using the compositor)

There are a couple more things you can do to make your ice material look nicer:


Use the Layer Weight node to make reflections more intense at sharp angles.
Bump map the glossy shades separately from the diffuse shader, which is acting more like the floor under the ice. If you really wanted to be realistic you could use multiple objects and a glass shader, but it is quite unnecessary as separate bump mapping looks fine.  
Use two glossy shaders, one for sharp reflections and one for softer reflections.


Here's the node setup used for the ice material in the above image:



Note that it is possible that the bump mapping in your material has gone wrong in some way, causing the gray ice. But it's impossible to say without at least seeing the nodes.